var gdAlert = {
	container: "",
	overlay: "",
	
	
	open: function(text, type) {
		//set message
		gdAlert.container = document.getElementById("alert_message");
		var title = '';
		switch(type){
			case 'error':
				title = 'Error';
				break;
			case 'success':
				title = 'Success';
				break;
			default:
				title = 'Information';
		}
		gdAlert.container.getElementsByTagName("H2")[0].innerHTML = title;
		gdAlert.container.getElementsByTagName("SPAN")[0].innerHTML = text;
		gdAlert.container.getElementsByTagName("INPUT")[0].focus();
		gdAlert.container.getElementsByTagName("INPUT")[0].focus();
		
		//create site overlay
		gdAlert.overlay = document.createElement("DIV");
		gdAlert.overlay.style.width = gdAlert.getPageSize()[0] + "px";
		gdAlert.overlay.style.height = gdAlert.getPageSize()[1] + "px";
		gdAlert.overlay.style.backgroundColor = '#000000';
		gdAlert.overlay.style.top = '0';
		gdAlert.overlay.style.left = '0';
		gdAlert.overlay.style.position = 'absolute';
		gdAlert.overlay.style.zIndex = '9999';
		
		document.body.appendChild(gdAlert.overlay);
		
		//center messagebox
		var arrayPageScroll = document.viewport.getScrollOffsets();
        var winH = arrayPageScroll[1] + (document.viewport.getHeight());
        var lightboxLeft = arrayPageScroll[0];
		
		gdAlert.container.style.top = ((winH / 2) - 90) + "px";
		gdAlert.container.style.left = ((gdAlert.getPageSize()[0] / 2) - 155) + "px";
		
		new Effect.Appear(gdAlert.container, {duration: 0.2});
		new Effect.Opacity(gdAlert.overlay, {duration: 0.2, to: 0.8});
	},
	
	close: function() {
		new Effect.Fade(gdAlert.container, {duration: 0.3});
		new Effect.Fade(gdAlert.overlay, {duration: 0.3, afterFinish: function() {
			document.body.removeChild(gdAlert.overlay);
		}});	
	},
	
	getPageSize: function() {
	        
		var xScroll, yScroll;
		
		if (window.innerHeight && window.scrollMaxY) {	
			xScroll = window.innerWidth + window.scrollMaxX;
			yScroll = window.innerHeight + window.scrollMaxY;
		} else if (document.body.scrollHeight > document.body.offsetHeight){ // all but Explorer Mac
			xScroll = document.body.scrollWidth;
			yScroll = document.body.scrollHeight;
		} else { // Explorer Mac...would also work in Explorer 6 Strict, Mozilla and Safari
			xScroll = document.body.offsetWidth;
			yScroll = document.body.offsetHeight;
		}
	
		var windowWidth, windowHeight;
	
		if (self.innerHeight) {	// all except Explorer
			if(document.documentElement.clientWidth){
				windowWidth = document.documentElement.clientWidth; 
			} else {
				windowWidth = self.innerWidth;
			}
			windowHeight = self.innerHeight;
		} else if (document.documentElement && document.documentElement.clientHeight) { // Explorer 6 Strict Mode
			windowWidth = document.documentElement.clientWidth;
			windowHeight = document.documentElement.clientHeight;
		} else if (document.body) { // other Explorers
			windowWidth = document.body.clientWidth;
			windowHeight = document.body.clientHeight;
		}	
	
		// for small pages with total height less then height of the viewport
		if(yScroll < windowHeight){
			pageHeight = windowHeight;
		} else { 
			pageHeight = yScroll;
		}
	
		// for small pages with total width less then width of the viewport
		if(xScroll < windowWidth){	
			pageWidth = xScroll;		
		} else {
			pageWidth = windowWidth;
		}
	
		return [pageWidth,pageHeight];
	}
}

//overwrite the alert function
var alert = function(text, type) {
	gdAlert.open(text, type);
}